Deep water lay barge and method



Oct. 13, 1970 c. w. SHAW 3,533,244

DEEP WATER LAY BARGE AND METHOD Filed Oct. 17, 1966 3 ShGBQS-ShBBt l I NVEN TOR.

CLARENCE W SHAW BY ATTORNEYS Oct. 13, 1970 c. w. SHAW DEEP WATER LAYBARGE AND METHOD 3 Sheets-$heet 2 Filed Oct. 17, 1966 INVENTOR. CLHRENCEW SHAW BY 7 ATTORNEYS Oct. 13, 1970 c. w. SHAW DEEP WATER LAY BARGE ANDMETHOD Filed Oct. '17, 1966 3 Sheets-Sheet 5 INVENTOR. CLARENCE W SHHHTTORNEYS United States Patent 3,533,244 DEEP WATER LAY BARGE AND METHODClarence W. Shaw, Metairie, La., assignor, by mesne assignments, to J.Ray McDermott and Co., Inc., N w Orleans, La., a corporation of DelawareContinuation-impart of application Ser. No. 364,933, May 5, 1964, nowPatent No. 3,321,925, dated May 30, 1967. This application Oct. 17,1966, Ser. No. 587,288

Int. Cl. B63h 25/06, 23/08; F16i N00 US. Cl. 6172.3 9 Claims ABSTRACT OFTHE DISCLOSURE The present invention is an improvement on the inventiondisclosed in my copending application Ser. No. 364,933, filed May 5,1964, now U.S. Pat. 3,321,925, of which copending application theinstant application is a continuation-in-part. This invention relates toa pipe laying barge and particularly to improvements thereof.

In marine pipe laying operations the usual procedure is to join milllengths of pipe together, on a barge, by butt welding and launch theminto the water from the barge. This is actually accomplished by movingthe barge forward a distance equal to the length of the pipe joint lastWelded, stopping the barge and aligning and welding another joint. Oftensuch barges are provided with means to contact the ocean bottom in somemanner to control the position of the barge and to pull the bargeforwardly in steps. That system is for relatively shallow water. Themeans to contact the ocean bottom is in some cases long cables which arecontrolled by winches whereby the barge can be quickly and accuratelymoved along and stopped for each pipe joint welding operation.

Usually steel pipe for underwater use is coated with a corrosionpreventing material, and in the larger pipe sizes, weights or weightedcoating must be added to prevent the pipes buoyancy from bringing it tothe surface. In the larger pipes, such coatings may be concrete forweight, which is substantially rigid. Such weight coatings usually aredesigned to give the empty pipe a specific gravity of from 1.05 to 1.50.In launching such pipe from the horizontal or straight position on thebarge, it must be allowed to bend convexly on the upper surface in itspath to the bottom and gain concavely on its upper surface as itapproaches the ocean floor to a horizontal position again. The pipe isthus subject to stress and movement from wave action, current and tidesand as the depth and weight increase the strains and curvature becomeunmanageable and the pipe and/or pipe coatings are damaged or destroyed.

According to the invention the portion of the pipe extending from thebarge to the bottom is held under forward tension, that is, tensionexerted in the direction of movement of the barge. It is a relativelyeasy matter to maintain a uniform and constant tension on the pipe whenthe barge is moving forwardly at a substantially uniform speed. However,when the operation is intermittent, such as is necessary when successivelengths of pipe are welded, on the barge to the string of pipe beinglaid, the barge must be brought to a standstill for each weldingoperation. Whether the barge is advanced forwardly by means of its ownpropellers or cables and winches, when it is stationary for a weldingoperation, there is always the likelihood of lateral or rearwardmovements which tend to relieve the tension on the pipe and createbending stress problems in the pipe. For example, wave action can causethe barge to rise and fall sufficiently to change the pipe tension quitematerially even though the barge may not be moving rearwardly orforwardly. Also, after a barge has been moved forwardly one step andthen brought to a standstill, there is often a rearward surge or slightmovement rearwardly, which tends to relieve tension on the pipe andcause the same to bend beyond the desired limits.

The present invention seeks to overcome this disadvantage by providingmeans whereby the tension on the pipe is maintained constant at alltimes irrespective of any movement of the barge and in any direction. Ingeneral, the invention comprises restraining means for frictionallyengaging the pipe so that forward movement of the barge will apply aforward force to the pipe. A constant forward force is applied to thefriction means, relative to the barge, so that the tendency to pull thepipe forwardly exists and is exerted even though the barge may be movingrearwardly or in any other direction that would tend to relieve pipetension.

Pipe laying barges of the type referred to usually comprise a downwardlyand rearwardly sloping ramp at one side of the barge, down which thepipe is guided into the water. The barge is provided with generallycentrally located propeller means for propelling the same forwardly andwhen tension is applied to the pipe, it is obvious that the forwardpropelling force, being applied along the center line of the vehicle,and the pipe tension acting along a laterally displaced line, tends tocause the barge to yaw or turn toward the side along which the pipeextends. Furthermore, the portion of the pipe suspended between thebarge and the bottom is subject to water movements which can cause undueswaying or vibrations in the pipe. The propeller wash from the bargepropeller accentuates this tendency since it disturbs the water in theregion of the suspended pipe. Both of the above difficulties areovercome by the present invention by providing a system of guided vanesadjacent but rearwardly of the propeller, which vanes not only directthe propeller wash away from the suspended pipe but also maintain theproper heading for the barge in opposition to the tendency of pipetension to turn it sideways.

It is, therefore, an object of this invention to provide an improveddeep water lay barge capable of accurately maintaining its direction ofmovement even without contact with the bottom of the body of water onwhich the barge is supported and with a minimum agitation of pipessuspended between the barge and the bottom.

Another object of the invention is to provide a deep water lay bargecapable of maintaining uniform and constant tension on the pipe beinglaid irrespective of movements of the barge relative to the bottom.

Still another object is to provide an improved deep water lay barge ofthe type set forth wherein the improvements are relatively simple andeconomical yet highly reliable in operation.

Further and additional objects: and advantages will become apparent tothose skilled in the art as the description proceeds with reference tothe accompanying drawings wherein:

FIG. 1 is a highly schematic side elevational view of the rear portionof a barge embodying the present invention;

FIG. 2 is a top plan view of FIG. 1;

FIG. 3 is a rear elevational view of the barge of FIG. 1;

FIG. 4 is an enlarged schematic side elevational view of one form oftension applying means;

FIG. is a vertical sectional view taken along the line 5-5 of FIG. 4;

FIGS. 6, 7 and 8 are, respectively, schematic side elevational views ofdifferent embodiments of tension applying means; and

FIG. 9 is a fragmentary enlarged view with parts broken away of aportion of the apparatus shown in FIG. 8.

Referring first to FIGS. 1, 2 and 3, the barge 2 may be of any desiredor conventional form provided with the necessary accessories andapparatus for storing and welding pipe lengths into a continuous lengthof pipe 4. The pipe 4 is directed downwardly and rearwarly along asuitable ramp 6 into the water on which the barge 2 is buoyant. Thedrawings herein omit the pipe engaging and guiding means commonlyprovided in the ramp 6 and omit the usual buoyant members supportingthat portion of the pipe 4 rearwardly of the barge to control itscurvature to the bottom of the body of water. All those means are fullydisclosed in the copending application referred to above although othermore or less conventional equivalent means may be employed.

According to the present invention a pipe tensioning apparatus 8 ismounted on the barge in position to engage the length of pipe 4 and toapply restraint to relative movement between the barge and pipe. Severalmodifications of the tensioning means 8 will be described hereinafterbut in each case, it applies a forward tension to the pipe 4 at alltimes. The barge is preferably also provided with a separate clampingdevice 10 by means of which the pipe 4 may be fixedly clamped to thebarge during those intervals of time when an additional pipe joint isbeing welded in place. When the pipe is so clamped to the barge, thrustof the propeller 12 maintains tension on the pipe. The clamping means10, however, may be released so that the tensioning means 8 may operate.From FIGS. 2 and 3 it will be readily apparent that the tension in thepipe 4 applies a rearward force to the barge 2 at one lateral extremitythereof. Tension is maintained and the barge is propelled forwardly bypropeller means 12, customarily located along the center line of thebarge. Thus, the propeller means applies a forward force to the centerline of the barge and that force, coupled with the tension of the pipe4, will normally tend to cause the barge to turn or yaw to the right.Also, it will be apparent that the wash from propeller 12 will normallyspread out rearwardly of the barge and cause considerable wateragitation in the region of the downwardly and rearwardly extendingportion of pipe 4 where it is suspended in the water. That agitationcould cause swaying or movements of the pipe that might introduceunwarranted and excessive bending stresses therein. To overcome both ofthe above disadvantages, the barge is provided with a system of vanes 14adjacent but rearwardly of the propeller means 12. The system of vanescomprises individual rudder-like vanes 16, each mounted for pivotalmovement on a vertical axis defined by a shaft 18. The shafts 18 arejournalled at their lower ends in a bracket or supporting structure 20and are journalled near their upper ends in suitable bearing means 22.As shown, three such shafts and vanes are provided so as to extendlaterally across an area wider than the propeller means 12 and inposition to intercept all of the propeller wash rearwardly thereof. Attheir upper ends the shafts 18 are each provided with a crank arm 24 andthose crank arms are joined by a pivoted link 26, one end of which ispivotally connected to a suitable tiller bar 28 or the like. Thus, whenthe tiller bar 28 is pivoted about its vertical pivot axis 30, the link26 will be moved laterally and thus swing all of the vanes 16 in thesame direction. As shown in FIG. 2, the vanes 16 are tilted in suchdirection as to intercept all of the wash from propeller 12 and directit laterally to the left. This action not only deflects propeller washaway from the suspended pipe 4 but also applies a counterclockwisemovement to the barge to overcome the tendency of the latter to yaw tothe right in the manner previously referred to.

Referring now to FIG. 4, which shows a first embodiment of pipetensioning means 8, there is shown thereln a bracket or frame structure32 mounted on the ramp 6 and straddling the pipe 4. Journalled on thebracket structure 32 is a pair of rubber-tired friction wheels 34 and 35arranged to frictionally engage the outer surface of the pipe 4. Asshown, the axle 36 upon which the lower wheel 35 is fixed, carries agear 38 fixed thereon, meshing with a second gear 40 rotatably carriedby the bracket frame 32 and which is fixed relative to a sprocket wheel42. The axle 44 upon which the upper wheel 34 is fixed has a sprocketwheel 46 fixed thereto. The sprocket wheels 42 and 4-6 are drivinglyconnected by means of a suitable chain 48 so as to ensure synchronousrotation of the wheels 34 and 35 and the gears 38 and 40 cause thosewheels to rotate in opposite directions whereby the portions thereofengaging the pipe 4 move in the same direction.

The lower axle 36 has a sprocket wheel 50 fixed thereto and is driven bya chain 52 from a constant torque motor device 54. The motor device 54is of a known type and may be described as an eddy currentelectrodynamic torque applying means. This motor has the ability ofdriving a load with a constant applied torque and of holding saidapplied torque even when stationary or when the unit is being forciblyrotated rearwardly against the applied torque. Thus, at all times itapplies a uniform and constant torque to the lower axle 36 in adirection to urge the lower wheel 35 to rotate in a clockwise direction,as seen in FIG. 4. Obviously, through the described gearing and chains48 the same constant torque will be applied to the upper wheel 34 in adirection to cause it to urge the pipe 4 forwardly. Hereinafter in thisspecification applicant will refer to forward rotation of the wheels 34and 35 as being that direction of rotation which tends to pull the pipe4 forwardly on the barge 2.

It will be obvious that, with the unit 54 energized, it will apply apredetermined tension on the pipe 4 and that tension will be maintainedconstant irrespective of whether the barge is moving forwardly, isstationary, or is actually surging rearwardly or even when it is risingand falling due to wave action.

The form of the invention shown in FIG. 6 is similar to that of FIG. 4and like parts bear the same reference numerals. In this embodiment,however, the eddy current unit 54 is replaced by a hydraulic drivesystem comprising a pump 56 driven by a suitable motor or other primemover 58. The pressurized fluid delivered by the pump 56 is fed througha conduit 60 to a fluid pressure operated motor 62, the output of whichis drivingly connected to the chain 52 to drive the tensioning means ina forward direction. A return conduit 64 from motor 62, extends througha hydraulic relief and bypass valve arrangement 66. A heat exchangingreservoir 68 is also provided to hold and cool a supply of hydraulicliquid and to deliver the same to the intake 70 of the pump 56. Therelief and bypass valve means 66 may be of conventional form andoperates to control return of liquid through conduit 64 so as tomaintain a predetermined and uniform operating pressure in the motor 62,or to completely bypass the output of pump 56 to the reservoir 68. Thefigure is merely schematic and suggests only one possible arrangement ofhydraulic circuits, it being obvious to those skilled in the art how auniform torque hydraulic motor may be employed to apply and maintain auniform and constant tension on the pipe 4.

FIG. 7 is a further embodiment, shown schematically, and in which partssimilar to those previously described bear the same reference numerals.In this embodiment a variable speed motor 72 drives the chain 52 througha fluid coupling or fluid fly wheel device 74. Such fluid couplings areknown in the art and need not be described in further detail. It is aknown characteristic of such devices that the torque transmittedtherethrough is proportional to the speed of the motor 72. Thus,regulation of the speed of motor 72 predetermines the actual torquetransmitted to chain 52 and thus to the wheels 34 and 35 which applytension to the pipe 4. As is customary, the fluid coupling 74 isprovided with an external circuit for the fluid therein and whichcircuit includes a heat exchanger 76 for maintaining the liquid at adesired Working temperature. In operation of such fluid couplingdevices, the oil customarily used develops considerable heat andconstant cooling is necessary.

In the embodiment of FIG. 8, the bracket frame 32 is not mounted orfixed directly on the ramp 6 but is mounted on a carriage 7 8 providedwith wheels 80 riding on suitable guide rails 82, which in turn arefixed on the ramp 6. The chain 52 is not driven in this embodiment toapply any pipe-tensioning torque to the wheels 34 and 35. Instead, thechain 52 is drivingly connected to a drum 84 (see FIG. 9) in a brakingunit 86. Within the unit '86 brake shoes 88 and 90- are provided andwhich are movable into engagement with the drum 84 by springs 92 and 94.Suitable adjusting means 96 are provided to adjust the compression ofspring 92 whereby to predetermine the extent of the braking effect andthereby predetermine the tension applied to pipe 4 upon forward movementof the barge 2. Preferably, the braking unit 86 contains a suitable oilor other liquid 98 to control the temperature of frictionally developedheat and to prevent chatter. The spring 94 urges brake shoe 90 intoengagement with drum 84 but its effect can be relieved or overcome byapplying suitable fluid pressure to a conduit 100 leading into acylinder 102 in which piston 104 reciprocates. The piston rod 106 ofpiston 104 is connected at its outer end to the brake shoe 90 wherebysufiicient pressure in conduit 100 will retract brake shoe 90 againstthe force of spring 94 and thus materially reduce the braking effect ofthe unit 86. As previously described, in some instances or types ofoperation, the barge is brought to a standstill periodically to permitwelding additional pipe lengths onto the string of pipe. Thereafter, thebarge is caused to move forwardly. However, the friction brakearrangement applies a static friction to the drum 84 when the barge isstationary and at the commencement of forward movement of the barge aconsiderably higher tension in pipe 4 would be necessary to startrotation of drum 84 than the amount of tension necessary to maintainrotation of the drum after it is once started. In a manner to bedescribed, the high starting tension referred to increases the pressurein line 100 to thus reduce the actual torque necessary to start rotationof drum 84. Fixed to the ramp 6 is a bracket 108 to which a hydrauliccylinder 110 is secured, as at 111. A piston 112 is positioned in thecylinder 110 and its piston rod 114 extends rearwardly therefrom and isconnected, as at 116, to the carriage 78 upon which the frame 32 andbraking device '86 are mounted. A hydraulic pump 118, driven by anysuitable means, delivers pressure to an outlet conduit 120 and fromthere to a conduit 122 which is connected at one end thereof to therearward end of the cylinder 110 and which is connected at its other endto a pressure control valve 124 through which fluid is delivered to areservoir 126 and to the inlet 128 of the pump 118. As will be apparent,the valve 124 may be adjusted to provide any desired hydraulic pressurein the cylinder 110 rearwardly of the piston 112. That pressure, actingthrough piston rod 114, applies a forward traction force to the carriage78 and hence applies a forward tension to the pipe 4, since rotation ofthe wheels 34 and 35 is restrained by the braking device 86. As shown, aconduit 130' connects the reservoir 126 with the forward end of cylinder110 to provide a vent therefrom thus preventing entrapment of fluidpressure forwardly of the piston 112. The conduit 100, previouslyreferred to, is connected to a valve device 132 between the conduit 100and conduit 134 connected to the conduit 122, previously referred to.Thus, the pressure applied to the rear of piston 112 is also fed intothe valve device 132 which is set to remain closed until the fluidpressure exceeds a predetermined value. Thus, when the barge isstationary the springs 92 and 94 apply braking restraint to rotation ofdrum 84 and the hydraulic pressure acting on piston 112 applies aforward force to the carriage 78 to hold the desired tension in pipe 4.However, when the barge first starts to move forwardly the high staticfriction on the drum 84 would normally result in a sudden increase inpipe tension. Under these circumstances, forward movement of the bargealso increases the pressure rearwardly of the piston 112 since movementof the barge tries to pull cylinder 110 forwardly and pipe tensionresists forward movement of the piston 112. This increase in hydraulicpressure is fed through conduit 134 and is effective to open valve 132to transmit that pressure through conduit into cylinder 102 and thuscompress spring 94 and relieve at least part of the bra-king force onthe drum '84. The parts are so constructed and adjusted that theremaining braking force will just maintain the desired tension on thepipe 4 during this starting interval. As soon as the drum 84 starts torotate, due to forward movement of the barge, the pressure in cylinderreturns to that value determined by the output of pump 118 and thesetting of valve 124. At this time the valve 132 again closes and ventspressure from the cylinder 102 by means not shown but known to thoseskilled in the art, and the desired tension is maintained on pipe 4 atall times. A manual switch 136 is also provided for selectivelyrendering the valve 132 and brake release means inoperative duringwelding and no clamp, such as clamp 10 of the previous embodiments isnecessary, although one may be provided, if desired.

As stated previously, the apparatus shown in the figures is merely shownschematically to illustrate the principles of operation. Manymodifications will become obvious to those skilled in the art, forexample, separate torque applying means may be arranged for each of thewheels 34 and .35 rather than having those wheels drivingly connectedtogether by a chain such as that shown at 48. Furthermore, for deepwater operation and particularly when laying large diameter pipe, asingle wheel 34 or 35 or even a pair of wheels '34 and 35 would not besufficient to develop the necessary pipe tension. In such instances, itis contemplated that the number of wheels engaging the pipe will beincreased to any necessary number.

While a limited number of embodiments are shown and described herein, itis to be noted that the invention is not limited thereto but encompassesother embodiments falling within the scope of the appended claims.

I claim:

1. Apparatus for laying continuous nonbuoyant pipe in a body of deepwater which comprises:

a buoyant vehicle having guide means thereof for guiding said piperearwardly off said vehicle;

a friction means to frictionally engage the pipeline;

carriage means mounting said friction means with respect to saidvehicle;

means responsive to the force exerted by said pipeline upon saidcarriage means to detect fluctuations in the amount of tension in said.pipe caused by move ment of said buoyant vehicle;

control means to vary the frictional force applied to said pipeline inresponse to said fluctuation to maintain a substantially uniformpredetermined tension on said pipeline.

2. Apparatus as defined in claim 1 wherein said friction means comprisesat least one pair of opposed wheels frictionally engaging the surface ofsaid pipe.

3. Apparatus as defined in claim 1 wherein said fric tion meanscomprises at least one wheel, journalled on said vehicle, in frictionalrolling engagement with said pipe; and wherein said control meansconnected to said wheel to prevent rearward rotation thereof untiltension in said pipe exceeds a predetermined value.

4. Apparatus as defined in claim 1 wherein said control means comprisesa friction brake resisting rotation of said wheel; said wheel beingjournalled on a carriage movable on said vehicle in a directionlongitudinally of said pipe; and means for applying a substantiallyconstant forward force to said carriage.

5. Apparatus for laying a nonbuoyant pipe in a body of deep water whichcomprises:

a buoyant vehicle having guide means thereon for guiding said piperearwardly off said vehicle;

friction means comprising at least one pair of opposed wheels forfrictionally engaging the surface of said p p individual torque applyingmeans communicating with each of said wheels for yieldably applying asubstan tially constant force to said wheels tending to move said pipeforwardly of said vehicle; and

control means to prevent rearward rotation of said wheels until tensionin said pipe exceeds a predetermined value.

6. Apparatus as defined in claim wherein said torque applying meanscomprises a constant torque electric motor.

7. Apparatus as defined in claim 5 wherein said individual torqueapplying means comprise a hydraulic drive system which comprises:

a source of pressurized hydraulic fluid;

a hydraulic motor communicating with said source of fluid and capable ofgenerating torque from input of such pressurized fluid;

a heat exchanger for cooling and maintaining a reservoir of hydraulicfluid;

conduit means to conduct hydraulic fluid from said hydraulic motor tosaid heat exchanger; and

means responsive to said control means to regulate the flow of saidfluid through said conduit means to maintain desired operating pressureof said fluid in said motor. 8. Apparatus as defined in claim 5 whereinsaid individual torque applying means comprise:

a variable speed motor;

a fluid coupling driven by said variable speed motor and capable ofgenerating torque in response to the speed thereof; and

an external cooling circuit to maintain fluid within said coupling atdesired operating temperature.

9. A method for laying nonbuoyant pipe in a body of water from a buoyantvehicle under uniform predetermined tension which comprises:

applying a forward force to said vehicle of a magnitude at least equalto said predetermined tension; frictionally engaging said pipe on saidvehicle at a plurality of points on the surface of said pipe; applying aforward force to said pipe tending to move said pipe forwardly relativeto said vehicle; generating, from a point remote from said frictionalengagement, a response to total and cumulative tension exerted upon saidpipe relative to said vehicle as said pipe moves relative to saidvehicle; and controlling said frictional engagement of said pipe at saidplurality of points to maintain tension on the pipe at a predeterminedvalue.

References Cited UNITED STATES PATENTS 2,659,549 11/1953 Galin 6172.3 X2,910,835 11/1959 Timothy 61-72.3 2,924,328 2/1960 Lidderdale 6172.3 X3,101,693 8/1963 Schilling 114168 3,237,438 3/1966 Tesson 6l72.3 X3,262,275 7/1966 Perret 6l72.3 3,280,571 10/1966 Hauber et al. 6l72.13,321,925 5/1967 Shaw 6172.3 3,390,532 7/1968 Lawrence 61-72.3 3,400,5429/1968 Davis 61-72.6

JACOB SHAPIRO, Primary Examiner U.S. Cl. X.R. 114l68; 226-.-

